A STUDY OF MOLECULAR GAS IN THE CENTER OF THE S0 GALAXY NGC-4710

This paper discusses observations of the J = 2-1 transition of (CO)-C- 13 and (CO)-C-13 in the center of the Virgo Cluster S0 galaxy NGC 4710 . We use a simple model suggested by Wrobel & Kenney (1992) for the di stribution of molecular gas to obtain a value for the intensity ratio of the transitions J = 2-1 and J = 1-0 which is similar to that in oth er S0 galaxies and in spirals. Available information on the intensity ratio (CO)-C-12/(CO)-C-13 suggests that the molecular gas is optically thick. This assumption is used to set limits on the gas temperature w hich are consistent with values typical of the Milky Way. The line pro file observed at the center of the galaxy is complex, indicating the p resence of significant structure within the source. This profile is we ll reproduced by adding a small number of clouds to the model. Althoug h present data do not constrain the cloud properties, those clouds we employ are analogs of large Milky Way giant molecular clouds and contr ibute approximately 25% of the total mass of the molecular disk in the center of this galaxy. The model closely constrains the locations of clouds which produce structure at the red and blue ends of our line pr ofile. Differences in the shapes of the profiles in the J = 1-0 and J = 2-1 transitions can be qualitatively explained by the lack of cloud structure within part of the molecular disk northeast of the nucleus.